textproduct: Rapid City

KEY MESSAGES

- Severe thunderstorm risk today into the evening hours with damaging winds and large hail possible.

- Chance of severe weather with all hazards possible Thursday.

- Active pattern persists through the week with daily chances of showers and thunderstorms.

- Warming temperatures expected through the week into the weekend.

DISCUSSION

(This Evening Through Monday) Issued at 1218 PM MDT Mon Jun 1 2026

Water vapor imagery shows shortwave trough pushing through SE WY, NE CO, and the NE Panhandle with a closed upper low over northern MT. Southeasterly surface flow continues with weak moisture advection; low clouds around the Black Hills are eroding with diurnal heating and mixing ongoing.

Active southwest flow continues today with shortwave trough to eject through the region this afternoon and evening. Showers and thunderstorms will develop across the western half of the forecast area. Sufficient MUCAPE (~500-1000 J/kg) will be in place this afternoon as the boundary layer warms with effective bulk shear in excess of 45-50 knots. This combination will support the threat of severe weather from far NE WY through SW SD and the Black Hills. Forecast soundings show a well-mixed boundary layer with forecast DCAPE values ~800+ J/kg, supporting a wind threat with any stronger convection. Given the shear profiles, any robust updraft that gets rooted would have potential to produce large hail. Expect convection initiation around 21z this afternoon with the bulk of the convection and severe weather threat pushing east of our area after 02-04z.

Better severe weather threat exists across a more widespread area Tuesday as upper low begins to eject out of MT into southern Saskatchewan Tuesday afternoon. South-southeast low level winds will advect more substantial moisture into the area Tuesday. The result will be MLCAPE values around 1500-2500 J/kg Tuesday afternoon. The best overlap of instability with favorable shear will be from the central Black Hills to Rapid City and areas northward toward ND where effective bulk shear values around 35-50 knots are forecast. Convection is forecast to develop after 20-21z with supercellular structures possible. While there is some uncertainty regarding the depth and quality of moisture (and subsequent impact on tornado potential vs. more outflow dominant convection), all hazards will be possible Tuesday.

Active pattern persists through the week with daily chances of thunderstorms, with Thursday looking like the day where all ingredients best overlap. While much can change, Thursday has that look of a more classic northern Black Hills supercell day with ample shear, instability, southwest upper flow coupled with low-level moisture pooling/ESE flow around the northern Black Hills.

Upper level ridging is forecast to build over the region for the weekend with warm and generally dry conditions expected, at least for Saturday. More active pattern expected Sunday into early next week.

AVIATION

(For the 18Z TAFS Through 18Z Tuesday) Issued At 1124 AM MDT Mon Jun 1 2026

A low cloud layer is continuing to burn off over the South Dakota plains. Once that happens, mostly VFR conditions are expected. There are chances for thunderstorms this afternoon in western South Dakota that may bring MVFR/IFR conditions, especially with stronger storms.

UNR WATCHES/WARNINGS/ADVISORIES

SD...None. WY...None.